1. Field of the Invention (Technical Field)
The present invention relates to a method and apparatus for creating a composite of an individual face without the need for recall of discrete facial parts, through the evaluation of a series of computer-generated facial composites.
2. Background Art:
Humans have excellent facial recognition ability. Age, sex, race, intention, mood and well-being may be determined from the perception of a face. Additionally, humans can recognize and discriminate between an "infinity" of faces seen over a lifetime, while recognizing large numbers of unfamiliar faces after only a short exposure. Unfortunately, humans often have great difficulty recalling facial characteristics in sufficient detail to generate an accurate composite of the individual. As a consequence, current composite-drawing creation procedures, which depend heavily on recall of specific facial features, are not always adequate.
When the nature of the perceiver is fixed, such as when a witness is required to identify a criminal suspect, only the configuration and presentation of the stimulus facial print may be varied to facilitate recognition. To ensure success under these circumstances, the facial stimuli must provide adequate information, without including unnecessary details that can interfere with accurate identification. A body of research has attempted to uncover the important factors governing facial stimuli and methods of presentation that are most compatible with the recognition process. The most systematic studies of facial recognition have been conducted in the field of criminology.
Beyond the use of sketch artists, more empirical approaches have been developed to aid in suspect identification. The first practical aid was developed in Britain, between 1968 and 1974. J. Penry, "Photo-Fit," Forensic Photography, vol. 3(7), pp. 4-10 (1974). Termed "PhotoFit," this technique uses over 600 interchangeable photographs of facial parts, picturing five basic features: forehead and hair, eyes and eyebrows, mouth and lips, nose, and chin and cheeks. With additional accessories, such as beards and eyeglasses, combinations can produce approximately fifteen billion different faces. Initially, a kit was developed for full-face views of Caucasian males. Other kits for Afro-Asian males, Caucasian females and for Caucasian male profiles soon followed.
Alternatives to PhotoFit have since been developed. They include the Multiple Image-Maker and Identification Compositor (MIMIC), which uses film strip projections; Identikit, which uses plastic overlays of drawn features to produce a composite resembling a sketch (see Solso et al., "Prototype formation of faces: A case of pseudo-memory," 72 British J. of Psych 499-503 (1981)); and Compusketch, a computerized version of the Identikit process available from the Visitex Corporation. U.S. Pat. No. 4,676,753, Identification Kits, to Haggas, discloses an overlay based identification kit similar to Identikit.
The Compusketch software is capable of generating over 85,000 types of eyes alone. With no artistic ability, a trained operator can assemble a likeness 45 to 60 minutes. Because of such advantages, computer-aided sketching is becoming the method of choice for law enforcement agencies.
However, because Of its wide distribution, the PhotoFit system has generated the largest body of research on recognition of composite facial images. One study of PhotoFit compared memory for photographs of faces with memory for PhotoFit facial prints which have noticeable lines around the five component feature groups, reporting that subjects recognize the unlined photographs more easily. The presence of lines appears to impair memory, and random lines have the same effect as the systematic PhotoFit lines. G. M. Davies, H. D. Ellis, and J. W. Shepherd, "Face Identification--the Influence of Delay Upon Accuracy of Photo-Fit Construction," Journal of Police Science and Administration, vol. 6(1), pp. 35-42 (1978). Individuals display a high degree of recognition of photographs, but generally describe a human face poorly. At least three sources of distortion arise between viewing a suspect and a PhotoFit construction--"selective encoding of features," assignment to physiognomic type,.revreaction. and "subjective overlay due to context"--which contribute to the production of caricatures of a suspect rather than accurate representations. G. M . Davies, J. W. Shepherd, and H. D. Ellis, "Remembering Faces--Acknowledging Our Limitations," Journal of the Forensic Science Society, vol. 18, pp. 19-24 (1978).
The need to respond to suggestive stimuli or concentrate on specific facial parts is a failing of all currently used systems of generating facial prints. The introduction of bias is particularly sensitive, since the primary use of these systems is in the law enforcement and legal areas. Ideally, to avoid such bias, an unskilled witness should be able to generate a composite facial stimulus unaided and uninfluenced.
Moreover, humans employ different and multiple methods of facial recognition that involve processing dichotomies that vary between analytical, feature based, and holistic organizational strategies. Existing methods of creating facial composite prints appear to constrain some of these methods of recognition. A major conclusion from cognitive research is that the mechanics of Compusketch and its predecessors, PhotoFit, MIMIC, and Identikit, actually inhibit recognition, by forcing witnesses to employ a specific cognitive strategy; namely, constructing facial prints from isolated feature recall. Since facial recognition appears to also involve holistic processes, the single feature methodology may be inappropriate. Indeed, One study has suggested that the single feature approach may be a more serious source of recognition distortion than interference from an outside source. G. M. Davies and D. Christie, "Face Recall: An Examination of Some Factors Limiting Composite Production Accuracy," Journal of Applied Psychology, vol. 67, pp. 103-109 (1982).
Many of the problems and limitations of the existing identification systems may be eliminated by adopting a strategy for generating facial prints that exploits the well developed human skill for facial recognition, rather than individual feature recall. Moreover, the present invention has been designed so that it accommodates a wide variety of individual styles of cognitive processing, using a genetic algorithm to generate composite facial prints, evolving an individual facial print over generations, and using recognition as the single criterion for directing the evolutionary process.
The present invention is not primarily concerned with automated recognition of faces, but rather with permitting unskilled individuals to generate facial composites using a computer. Patent dealing with the former area of endeavor include U.S. Pat. No. 4,975,969, Method and Apparatus for Uniquely Identifying Individuals by Particular Physical Characteristics and Security System Utilizing the Same, to Tal; U.S. Pat. No. 4,841,575, Image Encoding and Synthesis, to Welsh et al.; U.S. Pat. No. 4,754,487, Picture Storage and Retrieval System for Various Limited Storage Mediums, to Newmuis; U.S. Pat. No. 4,449,189, Personal Access Control System Using Speech and Face Recognition, to Feix et al.; U.S. Pat. No. 4,179,686, System for Checking the Authenticity of Identification Papers, to Bonicalzi et al.; and U.K. Patent No. GB 2,231,699 A, Obtaining Information Characterizing a Person or Animal, to Sherman.
The genetic algorithm, first described by in 1975 by J. H. Holland, Adaptation in Natural and Artificial Systems (Ann Arbor: University of Michigan Press 1975), is a robust search algorithm based upon the principles of biological evolution. In essence, the genetic algorithm is a simulation of the evolutionary process, and makes use of the powerful operators of "natural" selection, mutation and crossover to evolve a solution to any complex design problem. Unlike other procedures Currently in use, a genetic algorithm is capable of efficiently searching a large sample space of alternative facial composites and of finding a "satisficing" solution in a relatively short period of time. Since such a genetic algorithm procedure can be based on recognition rather than recall, and makes no assumptions concerning the attributes of witnesses or the cognitive strategy they employ, it can find an adequate solution irrespective of these variables.